Engine Yard, which provides platform as a service to developers building cloud apps, added Microsoft's Windows Azure cloud to its line-up.

The company is best known for its open source architecture and ability to abstract the infrastructure layer of the cloud. Engine Yard's alliance with Microsoft allows it to put its open source cloud platform on top of Azure.

Engine Yard's partnership with Microsoft is one of a bevy of cloud alliances announced in recent days. Oracle partnered with Microsoft on Azure as well as Salesforce.com and NetSuite.

Under the arrangement with Microsoft, Engine Yard will focus on automation and orchestration as well as its open source cloud frameworks. For Engine Yard, the exposure to Azure customers could broaden its base.

Scott Guthrie, corporate vice president of Windows Azure, said that Microsoft is committed to working with developers who use open source languages and frameworks.

Engine Yard said that it will be available on the Azure Marketplace July 31.